If there is no substantial/significant/notable/etc. difference between the two lenses at 100mm, I would be inclined to use the 100mm macro on a shoot because it is lighter.

However, if the 70-200mm lens (at 100mm) has some sort of appreciable advantage over the 100mm macro lens, then extra weight would be unimportant to me, and I would use the bigger lens.

From what I believe I have read elsewhere in Canon Rumors , but am unable to find exactly, is that the macro lens is not recommended generally for portraits (?), and that the 70-200mm is preferred, along with primes such as the 135mm f/2L or the 85mm f/1.2L.

100L worked fine for me too. I don't notice all that much difference between the 100L and the 70-200L II in practice. My copy of the 100L might be a tad better than my 70-200L II at that focal length. Printed 24"x36" canvas print and it looks good. Chose the 100L because I did not have a sturdy enough tripod for the 70-200L II.

100L Macro definitely. The 70-200 is fine but when you get out of the 70 and 200 ranges, your AF may not be as good. With the primes you know where your focus is. Both lenses require a couple of clicks stopped down for maximum resolution. The 100L is MUCH MUCH lighter.

I've had the 100L Macro for a while, and I finally bit the bullet and UPS has the 70-200 2.8L IS II on their truck on the way to my house as we speak.

I'll give the definitive answer on why some diss the 100L Macro.

It's because it has the description "Macro". If it did not, most would rave about the sharpness and other non-macro aspects of this lens (It is a GREAT all-around lens). That's also why you hear no one complain about the macro qualities of this lens (unless you're comparing to the Zeiss).

I've got both and find that the 100L produces slightly more clinical feeling portraits for some reason whereas the zoom always has a lush but sharp feel. I can't explain it beyond that but I think I prefer using the zoom.

If there is no substantial/significant/notable/etc. difference between the two lenses at 100mm, I would be inclined to use the 100mm macro on a shoot because it is lighter.

However, if the 70-200mm lens (at 100mm) has some sort of appreciable advantage over the 100mm macro lens, then extra weight would be unimportant to me, and I would use the bigger lens.

From what I believe I have read elsewhere in Canon Rumors , but am unable to find exactly, is that the macro lens is not recommended generally for portraits (?), and that the 70-200mm is preferred, along with primes such as the 135mm f/2L or the 85mm f/1.2L.

Might anyone share thoughts or insight regarding this question?

Here are my thoughts: first, you should loosen up your perception of what a "portrait" lens is.

I have the 85mm f/1.2 lens, usually thought to be the near-perfect lens for portraits in the Canon lens lineup. It is wonderful, but I take a minority of my portrait assignments with this marvelous beast. One can take a great portrait with almost any lens, from ultra-wide (fisheye to 24mm) "environmental" portraits, to "normal" 35mm to 60mm lens "medium" shots, to super-tight, very long focal length portraits, with lenses up to even the 300-400 mm range. Think creatively. It's not that a 100mm lens would not produce extremely pleasing head and shoulder - and even tighter head-only shots; it's just that it would be preferable to have more focal length options, especially in the 70-200mm range which covers most of the best focal lengths for people shooting. That is why you should strongly consider the f/2.8 zoom, in addition to, or instead of the 100mm macro. It also affords you the cropping and perspective that you might prefer when you can't necessarily change the distance between you and your subject, all things for you to consider.

As to bokeh, well, as in all high contrast zooms like the great 70-200 mm f/2.8 IS II, bokeh is a little busy compared to many simpler single focal length lenses, but it is still very good compared to most zooms and is usually more than acceptable for narrow aperture portraiture. Significantly better bokeh than the zoom would require the 85mm f/1.2, the 135 f/2.0, the 200mm f/2.0, or, perhaps, yes, maybe (by a hair) the 100mm 2.8 macro.

I have them both, and there's really nothing in it at normal focusing distances. If only 100mm will do or I need to get very close, I'll take the lighter lens. They're both equally spectacular for portraits at 100mm, but I personally prefer to change focal length a bit to go allow me to take both tight head portraits and upper body group shots without having to change perspective too much - so invariably I find myself using the zoom.

In reference to David's (dafrank) reply about the range of focal lengths in portraiture, I agree completely and indeed use focal lengths other than 100mm for portraits. I asked my question with specific reference to the 100 focal length only because I remember reading that other--namely, non-macro--lenses seemed to have been preferred by folks commenting on the matter (I wish I could remember the thread where I read those comments). I wonder if nehemiah is on to something with his idea that a "macro" label could have something to do with perceptions of the lens as not ideally suited for portraiture compared with non-macro-designated lenses.

At any rate, this forum is as helpful as ever. I appreciate all the comments made so far, and I look forward to learning more about experiences others have had with either or both lenses.

I also have both. The technical look of the images from the 100 certainly has a certain "something", but for me, the 70-200mm f/2.8L IS II is my glass of choice for headshot/portrait work. If your portrait shoots are very static affairs, then the 100 will be fine. My shooting style tends to require a more dynamic flow, so the flexibility and rocket fast AF of the 70-200mm f/2.8L IS II makes it the hands down winner.

While exquisite background blur can be a beautiful element in a shot and make a meaningful contribution, it's plainly not the shot. Your subject is the main game and the more powerful feeling/dynamic/magic-moment etc is what you need to chase in a successful portrait. Like that old chestnut keeps reminding us, "Content is King".